1. Technical Field
The present invention relates to a cover of a lighting unit for a vehicle in which a first resin layer having a deep color is laminated in a predetermined position on the backside of a second resin layer having a light color on a surface side.
2. Related Art
In the related art lighting unit for a vehicle, a first resin layer 1 having a deep color (for example, a black color) is laminated in a peripheral edge position on the back side of a second resin layer 2 having a light color (for example, a clear color) on a surface side, as shown in FIG. 8. The reference numeral 1a denotes a seal leg formed along a peripheral edge portion on the back face of the cover.
To form the cover, a primary molded product (the first resin layer 1 having the deep color) formed by preblanking is moved and mounted, and is then inserted in metal molds a and b. The second resin layer 2 having the light color is subjected to postblanking and is thus laminated and molded. The designation G denotes a side gate for the injection molding of the second resin.
In the injection molding of the second resin 2 subjected to the postblanking, however, the first resin layer 1 subjected to the preblanking contacts the second resin 2 in a melting state which is subjected to the postblanking. As a result, a part of the first resin layer 1 is molten. Consequently, the molten first resin 1 is drawn by the flow of the second resin 2 as shown in an arrow A of FIG. 8 and is thus mixed into the second resin layer 2 as shown in 1b. Consequently, there is a problem in that an appearance is poor when a lighting unit is turned off and a light is not emitted to have a predetermined functional color when the lighting unit is turned on.
In JP-U-05-090708 <Japanese Utility Model application publication> (see FIGS. 9(a) and 9(b)), there has been disclosed a cover of a lighting unit for a vehicle in which a first resin layer 1 having a deep color is laminated and molded in a peripheral edge position on the back side of a second resin layer 2 having a light color (for example, a clear color) on a surface side, the cover having such a structure that a convex portion 4 to bring the first resin 1 in the postblanking of the second resin 2 is formed on the peripheral edge of the opening portion of the first resin layer 1 subjected to preblanking, a penetrating portion 1b of the first resin 1 is caught into the convex portion 4 and the penetrating portion 1b of the first resin 1 is not mixed into a light emitting portion 5 of the cover. An arrow in FIG. 9(b) indicates the direction of the flow of the second resin 2 injected into a metal mold.
However, the related art has various problems and disadvantages. For example, but not by way of limitation, in the cover described in JP '708 it is certain that the first resin 1 is not mixed into the light emitting portion 5 of the cover, and the shape of the cavity of the metal mold becomes complicated, corresponding to the convex portion. Also, the size of the light emitting portion 5 is reduced corresponding to the convex portion 4 so that the light emitting area of the cover is decreased when a lighting unit is turned on. Furthermore, there is a problem in that the peripheral edge portion (the convex portion 4) of the light emitting portion 5 constituted by a single layer of a second resin looks dirty when the lighting unit is turned off and the appearance is thus poor.